1. Field of the Invention
The present invention relates to a dual tube fluorescent lamp and a lighting device using the dual tube fluorescent lamp. The dual tube arrangement includes an inner luminescence tube contained within an outer tube.
2. Description of Related Art
Although it is known to use a dual tube type fluorescent lamp, there is a perceived need to provide a dual tube fluorescent lamp which is bent to a predetermined shape that may include one or more bent or nonlinear portions.
The manufacture of a dual tube type fluorescent lamp having a nonlinear portion by known methods is rather complicated. After manufacturing a substantially linear dual tube type fluorescent lamp, a portion of it must be bent. The portion to be bent into some nonlinear shape is heated over a gas flame or by an electric furnace. The outer glass tube and the inner luminescence tube are softened and then bent into the desired shape.
During this heating and bending it becomes difficult to control both the inner luminescence tube and the outer tube such that they do not come into contact with one another. If they do, either or both of the tubes will become mis-shaped or ruined. Also, cracks may form in one or both of the tubes. There has been a need to find a better way of manufacturing dual tube type fluorescent lamps having non-linear portions.